Try this:
self.navigationItem.hidesBackButton = NO;
if you're trying to add it to the Navigation bar then:
UIImage* image4 = [UIImage imageNamed:@".....png"];
button = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 26, 26)];
[button setBackgroundImage:....png forState:UIControlStateNormal];
[button addTarget:self action:@selector(Selector)
forControlEvents:UIControlEventTouchUpInside];
[button setShowsTouchWhenHighlighted:YES];
UIBarButtonItem *action = [[UIBarButtonItem alloc] initWithCustomView:button];
NSArray *arr =[[NSArray alloc]initWithObjects:action, nil];
self.navigationItem.rightBarButtonItems = arr;